Plastic container and method of manufacturing the same

ABSTRACT

A plastic container contains a liquid, such as toilet water or soy source, and is suitable for containing a refill. The plastic container ( 1 ) has a tube ( 2 ) formed by rolling a plastic laminate in a tubular shape, a bottom wall ( 3 ) formed so as to be joined to the inner circumference of a lower end part of the tube ( 2 ) by an insert injection molding process, a hoop ( 4 ) formed on the outer circumference of an upper end part of the tube ( 2 ) by an insert injection molding process and a top cover ( 6 ) provided with a spout ( 5 ) and bonded to the upper end surface of the hoop

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a plastic container forcontaining a liquid, such as toilet water or soy source and, moreparticularly, to a plastic container for containing a refill and amethod of manufacturing such a plastic container for containing arefill.

[0003] 2. Description of the Related Art

[0004] A known cartridge, i.e., a plastic container, capable of sealinga fluidic material, such as an adhesive, therein is formed by insertinjection molding using a mold.

[0005]FIG. 5 shows a known cartridge 101 formed by insert injectionmolding using a mold. The cartridge 101 has a tube 102 of a plasticlaminate, a bottom molded part 103 joined to a lower end part of thetube 102, a top molded part 104 joined to an upper end part of the tube102, and a bottom member 106 of a plastic laminate bonded to the lowerend of the bottom molded part 103. When forming the cartridge 101 byinsert injection molding, a mold inserted in the tube 102 must becapable of being extracted from the tube 102. Therefore the innercircumference of the tube 102 must be smooth and must not haveirregularities and the tube 102 must be slightly tapered from its lowerend on the side of the bottom molded part 103 toward its upper end onthe side of the top molded part 104.

[0006]FIG. 6 is a sectional view of assistance in explaining a method ofmanufacturing the known cartridge 101. The tube 102 has the shape of atube having opposite open ends. The tube 102 is put on a mandrel 100,i.e., a metal core, tapered from its lower end toward its upper end.When the mandrel 100 holding the tube 102 is set in a mold 111, amolding cavity 103 a corresponding to the annular bottom molded part 103of the cartridge 101 is formed around the lower end part of the tube102, and a molding cavity 104 a corresponding to the top molded part 104is formed around the upper end part of the tube 102. The moldingcavities 103 a and 104 a are connected to a runner 112 formed in themold 111. After the tube 102 has been thus set in the mold 111, a moltensynthetic resin, such as a molten polyethylene resin through a gate 113formed in the mold 111 and the runner 112 into the molding cavities 103a and 104 a by an insert injection molding means. Thus, a body havingthe tube 102 provided with an annular bottom molded part 103 on itslower end part and a top molded part 104 joined to the upper end of thetube 102, and having an open bottom end is formed.

[0007] Since the cartridge 101 is formed by insert injection moldingusing the mold, the bottom molded part 103 must be formed in an annularshape on the lower end part of the tube 102 when the top molded part 104having an outlet opening is joined to the upper end of part of the tube102. Since the bottom molded part 103 is open, the bottom member 106 ofthe plastic laminate similar to that forming the tube 102 must be joinedto the lower end of the bottom molded part 103 by heat sealing.

[0008] Since the bottom member 106 of the plastic laminate is joined tothe bottom molded part 103 of the cartridge 101, gaps are liable to beformed in the joint 106 a of the bottom molded part 103 and the bottommember 106 if the rigidity of the bottom molded part 103 is insufficientand the bottom molded part 103 is loaded during transportation, and thecartridge 101 falls down easily. If the bottom member 106 of the plasticlaminate is bonded unsatisfactorily to the bottom molded part 103, thecontents of the cartridge 101 leaks through faultily bonded parts of thejoint of the bottom member 106 and the bottom molded part 103. Even ifthe bottom member 106 is bonded closely to the bottom molded part 103,the bottom member 106 of the plastic laminate is broken with a sharppoint and the contents leaks or the barrier property of the bottommember 106 is deteriorated.

SUMMARY OF THE INVENTION

[0009] The present invention has been made in view of the foregoingproblems and it is therefore an object of the present invention toprovide a plastic container having a rigid bottom wall formed by moldinga plastic material and resistant to the accidental formation of holestherein and the resultant leakage of the contents of the plasticcontainer.

[0010] A plastic container according to one aspect of the presentinvention comprises a tube of a plastic laminate, a bottom wall formedso as to be joined to the inner circumference of a lower end part of thetube by an insert injection molding process, a hoop formed on the outercircumference of an upper end part of the tube by an insert injectionmolding process, and a top cover provided with a spout and bonded to theupper end surface of the hoop.

[0011] Since the bottom wall is joined to the inner circumference of thelower end part of the tube and the hoop is joined to the outercircumference of the upper end part of the tube, a mandrel inserted inthe tube for insert injection molding can be extracted from the tube.Thus, the bottom wall and the hoop of the plastic container can beformed integrally with the tube by the insert injection molding processto complete the plastic container. The bottom wall thus formed by theinsert injection molding process is more resistant to breakage than thebottom wall of the plastic laminate.

[0012] In this invention, the term of “insert injection molding means”is used in the sense that the plastic container is manufactured in thesteps of:

[0013] forming the tube; putting the tube on a mandrel; inserting themandrel holding the tube in a mold; injecting a molten resin into thefirst and the second cavity to form the bottom wall and the hoop; andbonding the top cover.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The above and other objects, features and advantages of thepresent invention will become more apparent form the followingdescription taken in connection with the accompanying drawings, inwhich:

[0015]FIG. 1 is a perspective view of a plastic container in a preferredembodiment according to the present invention;

[0016]FIG. 2 is a sectional view of assistance in explaining a method ofmanufacturing the plastic container shown in FIG. 1;

[0017]FIG. 3(a) is a half sectional view of the plastic container shownin FIG. 1,

[0018]FIG. 3(b) is an enlarged part of A shown in FIG. 3(a).

[0019]FIG. 4 is a perspective view of assistance in explaining theapplication of the plastic container shown in FIG. 1 to a container forcontaining a refill;

[0020]FIG. 5 is a sectional view of a prior art cartridge (plasticcontainer); and

[0021]FIG. 6 is a sectional view of assistance in explaining a method ofmanufacturing the cartridge shown in FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Referring to FIGS. 1 and 3, a plastic container 1 in a preferredembodiment according to the present invention has a tube 2 formed from aplastic laminate, a bottom wall 3 formed so as to be joined integrallyto the inner circumference of a lower end part of the tube 2 by aninsert injection molding process, a hoop 4 formed so as to be joinedintegrally to the outer circumference of an upper end part of the tube2, and a top cover 6 provided with a spout 5 and bonded to the upper endsurface of the hoop 4.

[0023] The tube 2 is a tubular member having opposite open ends formedby rolling a rectangular plastic laminate in a tubular shape and bondingtogether the opposite side parts of the rectangular plastic laminate ina lap joint. The tube 2 may be formed by bonding together the oppositeside edges of the rectangular plastic laminate in a butt joint.

[0024] The plastic laminate is, for example, a flexible, opaquelaminated film formed by laminating a 30 to 60 μm thick polyethylenefilm, a 12 μm thick polyester film, a 9 μm thick aluminum foil and a 30to 60 μm thick polyethylene film. The plastic laminate may be atransparent laminated film formed by laminating a 30 to 60 μm thick castpolypropylene film, a 12 μm silica-coated film and a 30 to 60 μm thickcast polypropylene film.

[0025] As shown in FIG. 1, the top cover 6 has a circular flange 7having an outline coinciding with that of the hoop 4. The spout 5projects from a central part of the flange 7. A screw thread 8 is formedon the outer circumference of the spout 5 to screw a cap on the spout 5.Projections are formed at angular intervals on a part of the lowersurface of the flange 7 corresponding to the upper end surface of thehoop 4. The projections have a cross section of a shape substantiallyresembling a regular triangle, a width in the range of 0.5 to 0.7 mm anda height in the range of 0.5 to 0.7 mm.

[0026] Referring to FIG. 2, the tube 2 having opposite open ends ismounted on a tapered mandrel 10 serving as a core. When the mandrel 10holding the tube 2 is placed in a mold 11, a molding cavity 3 a formolding the bottom wall 3 of the plastic container 1 is formed insideone end part of the tube 2 and a molding cavity 4 a for molding the hoop4 is formed around the other end part of the tube 2. The moldingcavities 3 a and 4 a are connected to runners 12 formed in the mold 11.

[0027] After the mandrel 10 holding the tube 2 has been properly set inthe mold 11, a molten synthetic resin, such as a molten polyethyleneresin is injected through a gate 13 and the runners 12 formed in themold 11 into the molding cavities 3 a and 4 a by an insert injectionmolding machine. Thus, the bottom wall 3 and the hoop 4 are formedintegrally with the tube 2 to form a body having an open upper end.

[0028] Then, the top cover 6 is placed on the body with the projections7 c formed on the flange 7 in contact with the end surfaces of the hoop4, and the projections 7 c are crushed by vibrations exerted thereon byan ultrasonic welder to weld the flange 7 to the hoop 4. Thus, theplastic container 1 having the top cover 6 provided with the spout 5 isformed. The top cover 6 is provided with the flange 7 and the spout 5provided with the screw thread 8 a to screw a cap 8 on the spout 5. Asshown in FIGS. 3(a), (b) the projections 7 c are formed on the lowersurface of a peripheral part of the flange 7 at proper angularintervals. The projections 7 c are crushed by vibrations exerted thereonby the ultrasonic welder and, finally, the projections 7 c are mergedinto the hoop 4 and disappear.

[0029] The plastic container 1, similarly to conventional glass bottlesand molded plastic containers, is used for containing a liquid, such astoilet water or soy source and is capable of stably standing alone andresistant to the formation of minute leaks therein.

[0030] When the plastic container 1 is used for containing a refill, thehoop 4 is formed in an outside diameter equal to the inside diameter ofan open end part 20 a of an outer container 20, the flange 7 is formedin an outside diameter slightly greater than that of the hoop 4 so thata peripheral part 7 a of the flange 7 extends beyond the outercircumference of the hoop 4. The outer container 20 has a mouth part 20a provided with a screw thread 21 on its outer circumference. A holdingcap 24 has a side wall provided with a screw thread 22 on its innercircumference and a top wall provided with an opening 23 through whichthe spout 5 of the plastic container 1 projects outside.

[0031] The body 2 of the plastic container 1 is tapered from one end onthe side of the spout 5 toward the other end on the side of the bottomwall 3. Therefore, the plastic container 1 can be easily inserted in theouter container 20. Preferably, the outer container 20 is formed ofglass or a hard plastic material. In FIG. 4, the cap 8 is screwed on thespout 5 of the plastic container.

[0032] When assembling the plastic container 1 and the outer container20, the plastic container 1 is inserted in the outer container 20 fromits bottom upward so that the hoop 4 is fitted closely in the open endpart 20 a of the outer container 20 and the peripheral part 7 a of theflange 7 is seated on the upper end surface of the open end part 20 a ofthe outer container 20. Then, the holding cap 24 is screwed firmly onthe open end part 20 a of the outer container 20 with the screw thread22 engaging the screw thread 21 and the spout 5 of the plastic container1 projecting outside through the opening 23.

[0033] When the plastic container 1 is used for containing a refill, anempty plastic container 1 contained in the outer container 20 isreplaced simply with a new plastic container 1 containing a refill.Therefore any troublesome work for opening a pouch or the likecontaining a refill and pouring the refill in an empty container is notnecessary. Thus the plastic container can be easily put in the outercontainer 20 to refill the outer container 20, is excellent insanitation and is particularly suitable for containing food ortoiletries.

[0034] As apparent from the foregoing description, the plastic containeraccording to the present invention, similarly to conventional glassbottles and molded plastic containers, is used for containing a liquid,such as toilet water or soy source and is capable of stably standingalone and resistant to the formation of minute leaks therein. Whendisposing of the plastic container, the body can be squashed out and theplastic container can be compacted in a small mass.

[0035] Although the invention has been described in its preferredembodiment with a certain degree of particularity, obviously manychanges and variations are possible therein. It is therefore to beunderstood that the present invention may be practiced otherwise than asspecifically described herein without departing from the scope andspirit thereof.

What is claimed is:
 1. A plastic container comprising: a tube of aplastic laminate; a bottom wall formed so as to be joined to an innercircumference of a lower end part of the tube by an insert injectionmolding means; a hoop formed on an outer circumference of an upper endpart of the tube by an insert injection molding means; and a top coverprovided with a spout and bonded to an upper end surface of the hoop. 2.The plastic container according to claim 1 , wherein the top cover isprovided with projections in a part thereof corresponding to the hoop,and the projections are crushed by an ultrasonic means to bond the topcover to the hoop.
 3. The plastic container according to claim 1 ,wherein the plastic laminate is an opaque film including a metal foil.4. The plastic container according to claim 1 , wherein the plasticlaminate is a transparent film.
 5. A plastic container assemblycomprising: the plastic container of claim 1 ; an outer containercapable of containing the plastic container.
 6. The plastic containerassembly according to claim 5 wherein the tube of the plastic containeris tapered from its upper end toward its lower end.
 7. The plasticcontainer assembly according to claim 5 or 6 further comprising aholding cap having a side wall provided with a screw thread on its innercircumference; wherein the outer container has an open end part providedwith a screw thread on its outer circumference, and the holding cap isscrewed on the open end part of the outer container after inserting theplastic container in the outer container to fasten the plastic containerto the outer container.
 8. A method of manufacturing a plastic containercomprising a tube of a plastic laminate, a bottom wall formed so as tobe joined integrally to an inner circumference of a lower end part ofthe tube, a hoop formed so as to be joined integrally to an outercircumference of an upper end part of the tube, and a top cover providedwith a spout and bonded to an upper end surface of the hoop, said methodcomprising the steps of: forming the tube by rolling a plastic laminatein a tubular shape; putting the tube on a mandrel; inserting the mandrelholding the tube in a mold so that a first molding cavity connected to arunner formed in the mold, for molding the bottom wall of the plasticcontainer is formed inside one end part of the tube and a second moldingcavity connected to a runner formed in the mold, for molding the hoop isformed around the other end part of the tube; injecting a molten resinthrough the runners into the first and the second cavity by an insertinjection means to form the bottom wall and the hoop; and bonding thetop cover provided with the spout to an upper end surface of the hoop.